1. Field of the Invention
The invention relates to a controller, an electric power steering provided with the controller, a method of manufacturing bus bar, and method of manufacturing the controller.
2. Description of Related Art
For example, an electric power steering equipped with a steering assist electric motor includes a controller that controls the electric motor (for example, see Japanese Patent Application Publication No. 2009-188123 (JP-A-2009-188123) and Japanese Patent Application Publication No. 2009-247139 (JP-A-2009-247139)). The controller includes a power board that feeds driving electric power to the electric motor. A metal bus bar is connected to the power board. The bus bar is, for example, fixed between stacked plates as described in Japanese Patent Application Publication No. 2000-83311 (JP-A-2000-83311).
The bus bar described in JP-A-2009-247139 includes a first bus bar and a second bus bar. The first bus bar and the second bus bar are joined to each other by TIG welding. The first bus bar has a nickel plating layer. The nickel plating layer is connected to the electrode of the power board by wire bonding. In addition, the second bus bar has a tin plating layer. The terminal of a capacitor is joined to the tin plating layer by resistance welding.
In JP-A-2009-247139, as described above, the first bus bar suitable for wire bonding and the second bus bar not suitable for wire bonding but suitable for resistance welding are used. However, two types of bus bars, that is, the first bus bar and the second bus bar, need to be prepared, so it requires time and effort to manufacture the controller. In addition, the controller may be arranged in a narrow space, such as the front of a vehicle cabin, so it is desirable to reduce the size of the controller as much as possible.